#include<stdio.h>
#define CLK_TCK 100
int main() {
	int c1, c2;
	int count;

	scanf("%d%d", &c1, &c2);

	count = (c2 - c1) / CLK_TCK;

	if ((c2 - c1) % CLK_TCK >= 50)
		count = count + 1;


	printf("%02d:%02d:%02d", count / 3600, (count % 3600) / 60, (count % 3600) % 60);


	return 0;
}